The pediatric and adult transplant programs at Duke University Medical Center have served as a core clinical center for the BMT-CTN since its establishment in 2001. As a core center, Duke has made significant contributions to the network, including enrollment of 117 patients on CTN protocols, chairing two protocols (Dr. Kurtzberg chairs 0501 and Dr. Horwitz chairs 0901);serving on 6 protocol committees and 2 disease committees, authoring manuscripts and establishing and managing the immune reconstitution core for protocol 0501. The center has been in compliance with accurate and timely data and bio-specimen submission. The PI and Co-PI have regularly attended steering committee meetings and conference calls. Duke brings two specialized types of expertise to the CTN, (1) a long-standing and pioneering role in cord blood transplantation and banking and (2) unique experience in the treatment of pediatric patients with hematopoietic stem cell transplantation for non-malignant diseases. The study concept proposed in this application, based on ongoing work at Duke, will serve as the foundation for a follow-on study to BMT-CTN 0501. It is focused on furthering the understanding of the mechanisms that underlie engraftment after UCBT. Through analyses of banking (from the Carolinas Cord Blood Bank) and transplant outcomes at Duke, we have shown that dosing of colony forming units (CFUs) in thawed cord blood units best correlates with engraftment. Further analyses of additional parameters characterizing cord blood units before cryopreservation and after thawing allowed us to develop a predictive scoring system, coined the "cord blood apgar" (CBA) which, in a retrospective validation, most accurately determines cord blood potency and most closely correlates with engraftment potential. We propose to test and prospectively validate the CBA to optimize CBU selection in patients undergoing UCBT. The overarching goal of this work is to reduce engraftment delays and rates of primary graft failure after UCBT, increasing the overall success of UCBT. RELEVANCE (See instructions): The BMT-CTN is a highly important network of transplant centers working together to identify best practices and best therapies for patients with malignant and non-malignant diseases treated with transplantation. Duke has participated in the CTN since 2001 and has contributed significantly to its mission. The research proposal in this application will increase safety and efficacy of cord blood transplantation.